Watch crown and method of assembly



DeC- 4, 1956 E. L. SHAFRAN WATCH CROWN AND METHOD OF ASSEMBLY Filed sept. s, 1953 Edward Slzghm IN VEN TOR.

United StafCS Patent WATCH CROWN AND METHOD OF ASSEMBLY Edward L. Shafran, Chicago, ill.

Application September 8, 1953, Serial N o. 378,763

11 Claims. (Cl. 58-88) This invention relates to a watch crown and to a method for securing said crown to the winding and setting stem of a watch and, more particularly, to a crown assembly including a mass of securing material and a method for utilizing said material for securing said crown assembly on said stem.

Present methods of assembling crowns on the winding and setting stems of watches are so precise in nature as -to require factory installation by skilled technicians, and, in addition `to being time consuming, often result vin damage to either the watch movements or the stems. More particularly, in the most common present method of securing a crown to a watch stem, the setting lever screw of a watch movement is slightly released so as to permit the removal of the setting stem. If the setting lever screw is released more than a certain specified amount, the setting lever becomes detached from the movement and this necessitates repairing the watch movement. Following he removal of the stem from the movement, this stem is clamped in a pin vice and cut to a desired length by the use of either automatic apparatus or cutting pliers. There is a certain degree of danger inherent in the use of the pin vice for receiving the disassembled stem inasmuch as the stem may be nicked or lbent during the cutting operation.

Following the severing of the stern to a desired length, the end portion thereof is tapered and a crown, which has -been lbored and tapped through only a portion of its width, is threaded onto the stem. The crown is secured to the stem by means of a friction fit, and, accordingly, this method of securing the crown to the stem necessitates no-t only a very precise cutting operation on the stem but also an exact tapping operation so that the number of threads on the end of the stem exactly correspond with the number of internal threads in -the crown assembly.

Thereafter, the stem is removed from the pin vise and.

inserted in the watch movement and secured therein |by tightening the setting lever screw. If the length of the stern has been improperly gauged, as determined by Vthe position of the crown assembly relative to the watch movement following the insertion of the movement into a case, the entire operation set forth above must be repeated. Obviously, this prior method is quite time consuming and requires skilled personnel for its satisfactory accomplishment.

In another prior method, such as that disclosed and described in Frisk Patent 2,513,635, a number of the manual operations described above are obviated. However, this method also requires both a very accurate tapping of the crown assembly and accurate severing of the watch stem.

Accordingly, one object of this invention is to provide a quick and accurate method for sec-uring watch crowns to winding and setting stems.

Another object of this invention is to provide a watch crown which is capable of being assembled without precise and time consuming operations.

, 2,172,s6 'atented -lJec.4 4,

p A still further object resides in -the provision of a method of assembling watch crowns which does not require either exact tapping operations on the crown member or cutting the watch stem to a predetermined length.

Another object is to provide a crown assembly adapted to be positively secured to a winding and setting stem of a watch without relying on a friction iit between the crown and stem parts.

A still further object resides in the provision of a novel two-part watch crown assembly which is cheaply fabricated and does not require a precise tapping operation.

Another object is to provide a multipart crown assembly which includes a crown member having a tapped bore extending completely therethrough.

In accordance with these and many other objects, the invention includes a watch crown provided with a tapped bore extending completely therethrough in which is positioned a mass of displaceable securing material for joining winding and setting stems of varia-ble length to the crown assembly. In one embodiment of lthe invention, a two-part crown assembly is provided in which a crown member bored completely therethrough is provided with a recess or counterbore for receiving a mass of fusible material such as solder. A crown cap is placed over the crown member and cooperates therewith to define a cavity within which the solder is received. Following the cutting of a watch stem to a desired length, the stem is threaded into the crown member, and, thereafter, the crown assembly is subjected to heat in order to melt the solder so as to produce a bond between not only the two parts of the crown assembly but also -between the stem and the crown assembly. Obviously, sin-ce the mass of solder can be displaced and since the crown assembly is not secured to the stem by a friction lit, the crown assembly is adapted for use with stems of varying length.

In a second embodiment, a crown member is bored and ltapped throng-h its entire depth and a cap member having a depression or recess therein is secured on the crown member with the recess in alignment with the tapped bore so as to define a cavity within which is received a mass of fusible or displaceable securing material. Thereafter, a winding stem of a desired length is threadedly received within the tapped bore, and the assembled stem and crown assembly are subjected to heat to melt the mass of material so as to produce a bond between the stem and the various parts of the crown assembly.

In a further embodiment of the method of assembling the crown on the winding and setting stem, the severed length of the winding stem is threaded within the crown member, and, thereafter, a mass of fusible securing material is placed in a position adjacent -to both the outer end of the stem and the outer portion of the bore. Then, the cap member is mounted on the crown member, and the assembly is subjected to heat so that the fusible material unites the stem and both portions of the crown assembly. Since the tapped bore in the crown member extends complete-ly therethrough, the stem can also be severed after the crown member has been threaded on the stem so as to remove the gauging step described above.

Other objects and advantages of the present invention will become apparent from the ensuing description of illustrative embodiments thereof, in the course of which reference is had to the accompanying drawings in which:

Fig. l is a cross sectional view of a first embodiment of the crown assembly showing an assembled crown and windingr stem before the heating operation;

Fig. 2 of the drawings is a plan view in partial section of one type of apparatus for cutting a watch stem;

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Fig. 3 is an exploded View in partial section disclosing a modification of the method for securing a crown assem bly to a watch stem; A Y

Fig. 4 is a fragmentary elevational View in partial -section illustrating one manner of applying heat to an assembled crown and winding stem; A

Fig. 5 is a fragmentary top pian View of a device for applying heat to a watch crown assembly; and

Fig. 6 is a cross sectional vew of a modification of the multipart crown assembly shown in Fig. l of the drawings.

Referring now to Fig. 1 of the drawings, there is dis closed a first modification of a multipart crown assembly 10 embodying the present invention and including a crown member 12 having a tapped bore Al extending completely therethrough. The upper extremity of the bore 14 is enlarged, for instance, by a counterbore 16, to receive a mass of fusible material 18 such as a low melting point solder. A crown cap member 2o, provided with an annular corrugated depending portion or skirt 22, is posi- 'tioned'on the upper or outer surface of the crown mem ber 12 so as to cooperate with the enlarged portion 1o to define a cavity 24 -wit-hin which the fusible material 18 .is received. f

The lower surface of the crown member 12 is pro vided with a pair of concentric annular rings 26 and 28 of different diameters. The annular ring 28 is adapted to be received within a casing 34 of a watch movement to prevent the entryr of dirt into the watch movement. The outer annular periphery of the crown member 121 is provided with vertically extending corrugations or serrations which cooperate with oppositely formed corrugations 30 formed in the depending walls 4'22 of the crown cap 20. The cap preferably is formed of a precious metal such as gold, platinum, or silver inasmuch as this portion of the crown assembly 10' is exposed to view. The crown member 12, which is not visible, may be formed of any desired material, although a rust resistant material such as stainless steel may be desirable.

Inorder to secure the crown assembly 10 on a watch stem 32 of a conventional watch movement received within the watch case 34, the stem 32 is clamped between a pair of jaws 36 and 38 (Fig. 2) so as to rigidly secure the stem 32. If desired, the free end of the stem 32 may be received within a pin vice, indicated generally as 40, so asl to prevent bending of the stem 32 during a severing operation. Then, a gauge member 42 having a predetermined width isplaced in engagement with the stem 32 adjacent the clamping jaws 36 and 38 to indicate the amount of stem 32 which must be retained for receiving the crown assembly 10. Thereafter, conventional cutting pliers are utilized to sever and remove the excess length of the stem 32 by cutting this stem immediately adjacent the left hand surface of the gauge member 42, as disclosed in Fig. 2k of the drawings. Obviously, other suitable cutting methods and apparatus may be used to sever the stem 32.

The portion of the stem 32 projecting from the casing 34 is then threadedly engaged within the tapped bore 14 in the crown member 12 and the crown assembly 1d is advanced on lthe stem 32 until such time as it is properly positioned relative to the watch case 3d. This is easily accomplished with the crown assembly 1d of the present invention, inasmuch as the bore 14 extends through the entire crown member 12 and is not subject to the deficiencies of the present crowns wherein the bore extends only partially therethrough. Following the location of the crown assembly 10 relative to the watch case 34, the assembly lil-andthe stem 32 are displaced outwardly to the setting position of the stem to facilitate heating of the crown assembly.

To provide a means for heating the assembly 10, a heating member S0 (Figs. 4 and 5) is provided. This member may form the tip of a conventional soldering iron and is provided with a substantially flat axially extending portion 52 which includes a slot 5d of approximately the s ame width as the outer diameter of the de- Y pending ring 28. The slot 54 is terminated in a semicircle 56 having a radius of generation approximately equal to the radius of generation of the outer wall of the annular ring 2S. A semicircular recess 58, having a radius of generation approximately equal to the radius of generation of the outer wall of the depending portion 26, is formed in the flat portion 52 of the heating mem`s ber 50 adjacent the end ofthe slot 54. Y A

When it is desired to rigidly interconnect the stern 32 with the Vcrown assembly 1t), the annular portion 28 is introduced within the flared ends of the slot 54, and the heating member SG and crown assembly 10 are moved relative to each other until the annular ring 26 is received within the mating recess- 58. Thereafter, heat is applied to the crown assembly for aV short period of time in which the fusible mass of material 18 is melted so as to unite the two portions 2t) and 12 of the crown assembly 1) with the portion of the winding stem 32 ein tending into the member 12. After the heating, the member Si? is removed from engagement with the crown assembly 10, and the assembly is cooled for a few moments to permit the molten solder to solidify and produce a rigid interconnection betweenuthe assembled parts.

Since the watch stem 32 is displaced to its setting posh tion during the heating operation, the hot surfaces of the member 50 are not moved into engagement with vthe material forming 1the watch case 34 and, accordingly, any discoloration of the case 34 is prevented. Also, the configuration of the heating member 50 (Figs. 4 and 5) directs the heat to the crown assembly 10 and does not produce substantial heating of the elements of the watch movement so that the deleterious 'effects of destroying the temper of the elements forming the watch movement is positively prevented.

The advantages of the above described method of *as-V sembling a watch crown on a winding stem are manifest from consideration that the bore 14 is adapted to receive stems of varying length to obviate the necessity of provid'- ing either a crown assembly having a precisely tapped bore, or a winding stem 32 having an exact number of threads for being received within the tapped portion of a crown member. Further, since the stem 32 is severed following the mounting of the watch movement within the case 34, and, since the assembling operations are not damaging to the watch case, it is possible to properly locate the winding stem 32 relative to the aperture therefor in the case 34l prior to the time at which the crown assembly 1d is mounted on this stem.

A crown assembly 60, disclosed in Fig. 6 of the drawings, is a second modification of the novel watch crown forming the present invention and includes a crown member 62 having a bore 64 extending completely therethrough. A'cap member 66 is provided with a depression or recess 63'and is so mounted on the crown member 652 that the recess 68 is in communication with the bore 64. The recess 68 and cap 66 cooperate with the crown member 62 to' define a cavity 70 within which is received a mass of fusible material 72 such as a low melting point solder.

The crown member 62 also includes a pair of annularl depending rings 74 and 76 which are similar tothe annular rings 26 and 2S, respectively, in the crown assembly 10. The crown assembly 60 may be secured to the winding and setting stem 32 in the same'manner described hereinabove in conjunction with the crown assembly 10.

Fig. 3 of the drawings schematically illustrates a second manner inwhich thecrown assemblies 10fand60 can the counterbore 16 and the cap member 20 is positioned on the crown member 12. Then, the winding stem 32 is displaced to its setting position and the assembly is heated by the member 50, as disclosed in Fig. 4 of the drawings, so that the solder 18 is melted to join the members 12, 20, and 32.

Obviously, the crown assembly 60 could be secured to the watch stem 32 by utilizing the method described above by severing the watch stem 32 adjacent the outer surface of the crown member 62 and thereafter applying the mass of solder '72 to the end of the stem 32 and to the depression 68 in the crown member 62.

The method of assembly described in conjunction with Fig. 3 of the drawings obviates the necessity of utilizing the clamping jaws 36 and 38 and the gauging member 42 inasmuch as the crown members 12 and 62 are positioned relative to the casing 34 before the severing operation takes place, and, accordingly, insures that the stem 32 is cut to a proper length. However, the stem 32 could also be cut to a desired length prior to being threaded into the members 12 or 62 rather than following the assembly of the parts.

While the present invention has been described in connection with the details of illustrative embodiments, it should be understood that these details are not intended to be a limitation of the invention except insofar as set forth in the accompanying claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A crown assembly comprising a crown member having a bore therethrough, a cap member positioned on said crown member, said cap and crown members defining a cavity in communication with said bore, and a mass of bonding material positioned in said cavity.

2. A crown and stem assembly comprising a crown member having a bore therethrough, a cap member carried by said crown member so as to close one end of said bore to form a cavity open at one end, a stem mounted in said bore, and a mass of bonding material positioned in said cavity adjacent the closed end thereof for rigidly joining said cap member, said crown member, and said stem.

3. A crown assembly comprising a crown member having a bore therethrough, a cap member carried on said crown member so as to close one end of said bore to form a cavity open at one end, annular depending means formed on said crown member and encircling said bore adjacent the open end of said cavity, and a mass of bonding material positioned in said cavity and spaced inwardly from said annular depending means.

4. A crown assembly comprising a crown member having a bore therethrough, said member defining an enlarged opening at one end of said bore, a cap member mounted on said member and closing said enlarged portion to define a cavity, and a mass of fusible material positioned in said cavity.

5. A crown assembly comprising a crown member having a tapped bore therethrough, said member being counterbored adjacent one end of said bore, a cap member mounted on said member adjacent said counterbored portion to form a cavity in communication with said bore, an annular wall formed integral with said crown member adjacent the other end of said bore, and a mass of fusible material positioned in said cavity.

6. A crown assembly comprising a crown member having a bore therethrough, a cap member having a depression therein, said cap member being positioned on said crown member with said depression in alignment with said bore to define a cavity in communication with said bore, and a mass of displaceable securing material mounted in said cavity.

7. A crown assembly comprising a crown member having a tapped bore extending therethrough, a cap member having a recess therein, said cap member being positioned on said crown member with the recess in communication with said bore to define a cavity, and a mass of fusible material positioned in said cavity.

8. A crown assembly to be positioned on a winding stem comprising a crown member having a bore therein adapted to receive said stem, said crown member also defining an enlarged cavity in communication with said bore and spaced inwardly from the entrance to said bore, said cavity being bounded in part by a wall surface spaced across said cavity from the point at which the cavity opens into said bore, and a mass of bonding material positioned in said cavity and interposed between the end of said stem and said wall surface for securing said stem to said crown member.

9. The crown assembly defined by claim 8 in which the crown assembly includes a first crown member having said bore and a second crown member secured to said first member and providing said wall surface.

10. A method of assembling a two-part crown assembly on a watch stem extending outwardly from a watch casing which comprises inserting a watch stem into a first crown member so that the crown member is positioned adjacent said casing, severing said stem closely adjacent said first crown member on the side thereof spaced from said casing, placing a mass of bonding material on the assembled stem and first crown member, placing a second crown member over the first crown member, said first and second crown members defining a cavity within which the bonding material is disposed and into which the end of the stem extends, and heating the assembled first and second crown members and stem to render the bonding material effective to join the first and second crown members and to secure the assembled first and second crown members to the stem.

11. The method defined by claim l0 in which the bonding material comprises a fusible material and in which the fusible material is melted by said heating of the assembled first and second crown members to join said first and second crown members and said stem.

References Cited in the file of this patent UNITED STATES PATENTS 802,138 Byshe Oct. 17, 1905 811,705 Eaton Feb. 6, 1906 993,057 Grifiiths May 23, 1911 1,445,175 Schleip Feb. 13, 1923 1,477,657 Meyer Dec. 18, 1923 1,801,362 Mueller Apr. 2l, 1931 2,512,426 Hartley June 20, 2,585,997 Bruewer Feb. 19, 1952 FOREIGN PATENTS 2,203 Great Britain Jan. 26, 1884 226,489 Switzerland July 16, 1943 

